<h2>
The crime gets cleaned up at 2:00 PM</h2>
Step-by-step explanation:
Let the work be w.
Batman can clean up all of the crime in Gotham City in 8 hours working alone.
Robin can do the same job alone in 12 hours.
Robin starts work at 8:00 AM and Batman Joins at 10:00 AM.
Let the time of completion of work after Batman's joining be t.
We have time of working of Robin = t + 10:00 -8:00 = t + 2
So
After 4 hours of 10:00 Am work gets completed.
Time = 10:00 AM + 4 hours = 2:00 PM
The crime gets cleaned up at 2:00 PM
You need to ensure the denominators are the same. To do this you multiply the denominators together.
1/90 + 2/90
However, this is incorrect, as you need to do the same to the numerators, so for the left hand side you multiplied by 9 and for the right hand side you multiplied by 10, so you must do the same for the numerators.
So it should be:
9/90 + 20/90
You can now add this together, to get:
29/90
This is triple checked so I’m not sure why it says reduce the answer fully as that is as far as it can be reduced.
In this question , it is given that the land is 1.19 hectares. And the land developer splitting it into 9 identical properties . So to find the size of each property, we need to divide 1.19 by 9 and on doing that, we will get 0.13 hectares .
So the size of each property is 0.13 hectares .
If you're just starting calculus, perhaps you're asking about using the definition of the derivative to differentiate 
.
We have
Expand the numerator using the binomial theorem, then simplify and compute the limit.
In general, the derivative of a power function 
is 
. (This is the aptly-named "power rule" for differentiation.)
